The present invention relates in general to alerting and more particularly concerns novel apparatus and techniques for use with an X-ray inspection system, such as the commercially available AS&E MICRO-DOSE system used for inspecting baggage and other parcels for contraband, that automatically provides an alarm signal upon sensing potential contraband while separately displaying the item that may be the contraband to facilitate a rapid determination of whether concealed contraband is in the bag or package. These results are achieved with apparatus that is relatively inexpensive, reliable and advantageously employs existing components of an X-ray imaging system.
The problem of detecting contraband concealed in packages and baggage is a serious one. The AS&E MICRO-DOSE X-ray inspection system has helped solve this problem for a number of leading airlines while inspecting carry-on baggage and parcels. That system includes means for scanning a line X-ray detector with a pencil beam of X-ray energy to provide a line image signal characteristic of the X-ray response of the parcel being scanned, and a television display system for displaying the sequence of image signals derived from the line detector as the parcel moves past. The detector comprises sodium iodide crystals that produce a visible manifestation of the intensity of the incident radiation that is sensed by a photodetector to provide a characteristic video output signal that may be applied to the television display having an image storage tube. The television picture tube displays an image of the contents of the parcels being scanned so that the operator may identify objects that may be contraband, such as a gun, bomb or knife. This system has such a high resolution that it is possible in most cases to readily distinguish between the presence and absence of contraband. However, the operator must make a judgment based on observing the picture as to whether a particular parcel should be opened and manually examined. Should the operator fail to make a proper judgment, it is possible that a parcel containing contraband might not be detected.
Accordingly, it is an important object of the invention to provide apparatus and techniques for automatically alerting inspection personnel of the possibility of contraband in a parcel being inspected.
It is a further object of the invention to achieve the preceding object with apparatus that is reliable, relatively inexpensive and advantageously employs existing components of an X-ray inspection system.
It is a further object of the invention to achieve one or more of the preceding objects while presenting a separate display of an item that may be contraband to facilitate identification of contraband without opening the parcel where practical.
It is a further object of the invention to achieve one or more of the preceding objects by sensing objects having an X-ray opacity greater than a predetermined level.